The present invention relates generally to combustion engines, and more particularly, to a system and method of dynamically controlling an alternator winding configuration of a combustion engine in response to operating conditions. As such, engine operation is improved over a variety of operating conditions.
Modern recreational product engines have a variety of needs that require more electrical power. Specifically, in a recreational product, engine operation delivers power to an internal rail, from which power is directed to charge a battery, operate fuel injectors, operate fuel pumps, and the like. Furthermore, power is often directed to auxiliary systems and components such as lights, radios, CD and DVD players, televisions, and the like.
Therefore, in the design of modern recreational product engines, the quality and quantity of power delivered by the engine is of paramount importance. While it is possible to provide the higher levels of power with larger alternators that are capable of producing more current at a standard voltage level, such alternators are large, heavy, and relatively expensive. Therefore, it is advantageous to provide a hybrid alternator that is small and lightweight, yet has high power output capabilities. It is well known that the number of turns of the windings of an alternator governs the magnitude of the current that can be supplied by an alternator. When the rotor of the alternator is rotating at high speeds, providing enough power is not much a concern. However, in order to get enough power out of such an alternator at low speeds when the rotor is rotating more slowly, it is desirable for the windings to have more turns.
Therefore, in order to provide an alternator that is capable of supplying sufficient current at high and low speeds, switching alternator systems have been developed. Alternator systems, such as that described in commonly owned U.S. Pat. No. 6,066,941, include an alternator having multiple alternator coils for generating an AC power coupled through a plurality of diodes to first and second DC load buses. A plurality of switches are utilized to switch between a series winding configuration at low speeds of operation and a parallel winding configuration at high speeds of operation. That is, when in a series configuration, the windings are electrically configured so as to have numerous turns and, when in a parallel configuration, the windings are electrically configured so as to have fewer turns.
The switches are commonly thyristors that are triggered to switch by analog circuits such as an electronic control module (ECM) circuit that is configured to monitor the rotational speed of the alternator rotor. If the alternator rotor is rotating below a predetermined rotational speed, the voltage applied by the ECM circuit to the cathode of the thyristor relative to the anode is positively charged and, as such, the thyristors remain electrically closed and the windings are electrically configured to be in series. However, when the rotor of the alternator exceeds the predetermined rotational speed, the ECM circuit applies a negative charge to the cathode of the thyristors relative to the anode, which electrically switches the thyristors to open and electrically configures the windings in parallel.
While this system does provide the necessary switching alternator system adequately, it is limited in the amount and type of operational feedback that it can monitored to determine switching timing. That is, because the control circuit is an analog control circuit, adding additional feedback increases the size and complexity of the circuit correspondently. Furthermore, since the control circuit is analog, the thresholds for switching are predetermined and fixed. Therefore, the control circuit must be preconfigured to operate within a particular engine configuration and under known variable rotational speeds of the engine rotor.
It would be desirable to have a system and method for alternator switching that is dynamically adaptable to a variety of operating conditions and rotational speeds of the rotor. Furthermore, it would be desirable to have a switching system that is flexibly configurable to operate in multiple products and within different operating conditions and environmental requirements.